Obtenção de extratos de agaricus bisporus com ergosterol para incorporação em iogurtes e procedimentos de microencapsulação

Além de ser o cogumelo mais consumido no mundo, Agaricus bisporus é um dos cogumelos mais ricos em ergosterol, representando esta molécula quase 90% da sua fração de esteróis. Vários estudos têm atribuído ao ergosterol diferentes bioatividades, incluindo efeitos hipocolesterolémicos semelhantes aos exibidos pelos fitoesteróis. Isto torna o ergosterol uma molécula interessante para ser estudada como composto nutracêutico. Assim, este trabalho teve como objetivo avaliar o potencial de utilização dos extratos de A. bisporus ricos em ergosterol na produção de bebidas lácteas funcionais. Para o efeito, foram realizados testes de incorporação do extrato e do ergosterol puro em iogurtes que se compararam com bebidas lácteas funcionais comerciais (aditivadas com fitoesteróis). As amostras de A. bisporus foram submetidas a uma extração assistida por ultrassons e os extratos obtidos (IEXT), bem como a molécula de ergosterol em diferentes concentrações (IERG1 e IERG2), foram incorporados em iogurtes, e comparadas com amostras controlo (amostras de iogurte sem aditivos) (ICN) e iogurtes comerciais contendo fitoesteróis (ICP). Todas as amostras foram analisadas imediatamente após a incorporação (T0), e após sete dias de armazenagem a 4°C (T1), em relação aos parâmetros nutricionais, atividade antioxidante e propriedades citotóxicas em linhas celulares tumorais humanas e numa cultura primária de células de fígado de porco (não tumoral) para avaliação da toxicidade. O teor de ergosterol incorporado na forma pura, ou presente nos extratos, foi monitorizado por HPLC-UV. Adicionalmente, foi realizado um estudo de microencapsulação utilizando a técnica de coacervação, tendo o quitosano e o isolado proteico de soro como materiais encapsulantes. Num ensaio preliminar determinou-se o pH conducente a um maior rendimento de encapsulação e, seguidamente, verificou-se a influência da razão proteína:quitosano (P/Q) e da temperatura utilizada, no rendimento de encapsulação (Y1), na eficiência de encapsulação (Y2) e na carga (teor de ergosterol nas microesferas) (Y3). Posteriormente, o estudo foi realizado baseando-se nas melhores condições para encapsular ergosterol, sendo também avaliadas as respostas Y1, Y2 e Y3. Além de ser o cogumelo mais consumido no mundo, Agaricus bisporus é um dos cogumelos mais ricos em ergosterol, representando esta molécula quase 90% da sua fração de esteróis. Vários estudos têm atribuído ao ergosterol diferentes bioatividades, incluindo efeitos hipocolesterolémicos semelhantes aos exibidos pelos fitoesteróis. Isto torna o ergosterol uma molécula interessante para ser estudada como composto nutracêutico. Assim, este trabalho teve como objetivo avaliar o potencial de utilização dos extratos de A. bisporus ricos em ergosterol na produção de bebidas lácteas funcionais. Para o efeito, foram realizados testes de incorporação do extrato e do ergosterol puro em iogurtes que se compararam com bebidas lácteas funcionais comerciais (aditivadas com fitoesteróis). As amostras de A. bisporus foram submetidas a uma extração assistida por ultrassons e os extratos obtidos (IEXT), bem como a molécula de ergosterol em diferentes concentrações (IERG1 e IERG2), foram incorporados em iogurtes, e comparadas com amostras controlo (amostras de iogurte sem aditivos) (ICN) e iogurtes comerciais contendo fitoesteróis (ICP). Todas as amostras foram analisadas imediatamente após a incorporação (T0), e após sete dias de armazenagem a 4°C (T1), em relação aos parâmetros nutricionais, atividade antioxidante e propriedades citotóxicas em linhas celulares tumorais humanas e numa cultura primária de células de fígado de porco (não tumoral) para avaliação da toxicidade. O teor de ergosterol incorporado na forma pura, ou presente nos extratos, foi monitorizado por HPLC-UV. Adicionalmente, foi realizado um estudo de microencapsulação utilizando a técnica de coacervação, tendo o quitosano e o isolado proteico de soro como materiais encapsulantes. Num ensaio preliminar determinou-se o pH conducente a um maior rendimento de encapsulação e, seguidamente, verificou-se a influência da razão proteína:quitosano (P/Q) e da temperatura utilizada, no rendimento de encapsulação (Y1), na eficiência de encapsulação (Y2) e na carga (teor de ergosterol nas microesferas) (Y3). Posteriormente, o estudo foi realizado baseando-se nas melhores condições para encapsular ergosterol, sendo também avaliadas as respostas Y1, Y2 e Y3. As bebidas funcionalizadas com o extrato (IEXT) e com ergosterol na mesma concentração existente no extrato (IERG1) revelaram uma atividade antioxidante similar às bebidas comerciais com fitoesteróis. No entanto, as bebidas com ergosterol na mesma concentração do extrato de A. bisporus e de fitoesteróis (IERG2) revelaram uma atividade antioxidante superior. Além disso, apenas IEXT, IERG1 e IERG2 apresentaram um aumento na atividade antioxidante de T0 para T1, com destaque para a atividade exibida por IERG2, significando que o ergosterol e os extratos foram capazes de proteger a bebida láctea da oxidação, aumentando a vida de prateleira do produto. IERG2 foi a amostra que revelou a maior citotoxicidade para as linhas celulares tumorais, enquanto as bebidas com fitoesteróis mostraram a menor atividade, sem diferenças significativas entre T0 e T1. Os estudos de microencapsulação revelaram ainda que a técnica de coacervação permite obter cápsulas de distintos tamanhos e que as condições ótimas do processo ocorrem a pH 5,5, com temperatura de 55ºC e razão P/Q de 0,5, com um menor rendimento de encapsulação, mas com uma maior carga em ergosterol. Este trabalho contribuiu para o estudo do potencial da utilização de extratos de A. bisporus com ergosterol no desenvolvimento de novas bebidas funcionais. Constituiu um primeiro passo que necessita de estudos subsequentes relacionados com a avaliação da viabilidade da sua utilização ao nível industrial e demonstração clara da sua bioatividade in vivo.

Odour flux from litter of broiler chickens fed diets differing in protein levels and additives

The effect of dietary crude protein (CP) and additives on odour flux from broiler litter was investigated using 180 day-old Ross 308 male chicks randomly allocated to five dietary treatments with three replications of 12 birds each. A 5×3 factorial arrangement of treatments was employed. Factors were: diet (low CP, high CP, high CP+antibiotic, high CP+probiotic, high CP+saponin) and age (15, 29, 35 days). Low CP (LCP) and high CP (HCP) diets differed in CP levels by 4.5-5%. The low CP diets were supplemented with L-valine, L-isoleucine, L-arginine, L-lysine, D,L-methionine and L-threonine. The antibiotic used was Zn Bacitracin, the probiotic was a blend of three Bacillus subtilis strains and the saponin came from a blend of Yucca and Quillaja. Odorants were measured from litter headspace using a flux hood and selective ion flow tube mass spectrometry (SIFT-MS). Results were log tranformed and analysed by two-way ANOVA with repeated measures using JMP statistical software v.8, and means were separated by Tukey's HSD test at P<0.05.The results showed that LCP group produced lower flux of dimethyl amine, trimethyl amine, H2S, NH3 and phenol in litter compared to HCP group (P<0.05). Similarly, HCP+probiotic group produced lower flux of H2S (P<0.05) and HCP+saponin group produced lower flux of trimethylamine and phenol in litter compared to HCP group (P<0.05). The dietary treatments tended (P=0.065) to have higher flux of methanethiol in HCP group compared to others. There was a diet x age interaction for litter flux of diacetyl, acetoin, 3-methyl-1-butanol, 3-methylbutanal, ethanethiol, propionic acid and hexane (P<0.05). Concentrations of diacetyl, acetoin, propionic acid and hexane in litter were higher from LCP group compared to all other treatments on d 35 (P<0.05) but not on days 15 and 29. Thus, the low CP diet, Bacillus subtilis based probiotic and Yucca/Quillaja based saponin were effective in reducing the emissions of some key odorants from broiler litter.

Avaliação da técnica de dispersão da matriz em fase sólida assistida por vórtex para análise de fármacos em peixes

Os fármacos classificados como contaminantes orgânicos emergentes tornaramse tópico de discussão ambiental pois estes são capazes de atingir diferentes matrizes do meio ambiente, como água, solo e organismos aquáticos, e estudos demonstrando a toxicidade tem despertado o interesse científico. Neste estudo um método analítico foi otimizado e validado para determinação de quinze fármacos em amostras de peixes empregando preparo de amostras por dispersão da matriz em fase sólida (MSPD) assistida por vórtex e determinação por cromatografia líquida acoplada a espectrometria de massas sequencial (LC-MS/MS). O estudo ainda focou na aplicação de diferentes suportes sólidos na etapa de dispersão da MSPD, sendo que três (quitina, quitosana e concha de mexilhão dourado) foram utilizados pela primeira vez para esta finalidade, O método otimizado foi validado seguindo os parâmetros do INMETRO, ANVISA, SANCO e FDA. A curva analítica e linearidade foram avaliados através da calibração externa e superposição na matriz. Os compostos demonstraram linearidade dentro da faixa recomendada, com coeficiente de correlação maior do que 0,99. Os limites de detecção do método variaram de 1 a 100 ng g -1 , e os limites de quantificação a variaram de 5 a 1000 ng g -1 . Os valores de recuperação variaram de 68% a 108%, com RSD menores que 13% para todos os compostos. O efeito de matriz foi avaliado e quatro dos quinze compostos apresentaram efeito maior que ±20%. Na aplicabilidade o método demonstrou ser eficiente para extração de fármacos de diferentes espécies de peixe, apresentando exatidão e precisão adequados. Não foram encontrados resíduos de fármacos nas amostras analisadas.

Characterisation and quantification of changes in odorants from litter headspace of meat chickens fed diets varying in protein levels and additives

The effect of dietary crude protein (CP) and additives on odor flux from meat chicken litter was investigated using 180 day-old Ross 308 male chicks randomly allocated to five dietary treatments with three replicates of 12 birds each. A 5 × 3 factorial arrangement of treatments was employed. Factors were: diet (low CP, high CP, high CP+antibiotic, high CP+probiotic, high CP+saponin) and age (15, 29, 35 days). The antibiotic used was Zn bacitracin, the probiotic was a blend of three Bacillus subtilis strains and the saponin came from a blend of Yucca and Quillaja. Odorants were collected from litter headspace with a flux hood and measured using selective ion flow tube mass spectrometry (SIFT-MS). Litter moisture, water activity (Aw), and litter headspace odorant concentrations were correlated. The results showed that low CP group produced lower flux of dimethyl amine, trimethyl amine, H2S, NH3, and phenol in litter compared to high CP group (P < 0.05). Similarly, high CP+probiotic group produced lower flux of H2S (P < 0.05) and high CP+saponin group produced lower flux of trimethylamine and phenol in litter compared to high CP group (P < 0.05). The dietary treatments tended (P = 0.065) to have higher flux of methanethiol in high CP group compared to others. There was a diet × age interaction for litter flux of diacetyl, 3-hydroxy-2-butanone (acetoin), 3-methyl-1-butanol, 3-methylbutanal, ethanethiol, propionic acid, and hexane (P < 0.05). Concentrations of diacetyl, acetoin, propionic acid, and hexane in litter were higher from low CP group compared to all other treatments on d 35 (P < 0.05) but not on d 15 and 29. A high litter moisture increased water activity (P < 0.01) and favored the emissions of methyl mercaptan, hydrogen sulfide, dimethyl sulfide, ammonia, trimethyl amine, phenol, indole, and 3-methylindole over others. Thus, the low CP diet, Bacillus subtilis based probiotic and the blend of Yucca/Quillaja saponin were effective in reducing the emissions of some key odorants from meat chicken litter.

Produção de enzimas quitosanolíticas utilizando Paenibacillus ehimensis e Paenibacillus chitinolyticus para obtenção de quitoologossacarídeos

The acquisition of oligosaccharides from chitosan has been the subject of several studies in the pharmaceutical, biochemical, food and medical due to functional properties of these compounds. This study aimed to boost its production of chitooligosaccharides (COS) through the optimization of production and characterization of chitosanolytic enzymes secreted by microorganisms Paenibacillus chitinolyticus and Paenibacillus ehimensis, and evaluating the antioxidant potential of the products obtained. In the process of optimizing the production of chitosanase were employed strategies Fractional Factorial Experimental Design and Central Composite Rotatable Design. The results identified the chitosan, peptone and yeast extract as the components that influenced the production of chitosanase by these microorganisms. With the optimization of the culture media was possible to obtain an increase of approximately 8.1 times (from 0.043 to 0.35 U.mL U.mL-1) and 7.6 times (from 0.08 U.mL-1 to 0.61 U.mL-1) in the enzymatic activity of chitosanase produced by P. chitinolyticus and P. ehimensis respectively. Enzyme complexes showed high stability in temperature ranges between 30º and 55º C and pH between 5.0 and 9.0. Has seen the share of organic solvents, divalent ions and other chemical agents on the activity of these enzymes, demonstrating high stability of these crude complexes and dependence of Mn2+. The COS generated showed the ability of DPPH radical scavenging activity, reaching a maximum rate of scavenging of 61% and 39% when they were produced with enzymes of P. ehimensis and P. chitinolyticus respectively. The use of these enzymes in raw form might facilitate its use for industrial applications

Development of nanostructured hydrogel for spatial and temporal controlled release of active compounds

L’utilisation de nanovecteurs pour la livraison contrôlée de principes actifs est un concept commun de nous jours. Les systèmes de livraison actuels présentent encore cependant des limites au niveau du taux de relargage des principes actifs ainsi que de la stabilité des transporteurs. Les systèmes composés à la fois de nanovecteurs (liposomes, microgels et nanogels) et d’hydrogels peuvent cependant permettre de résoudre ces problèmes. Dans cette étude, nous avons développé un système de livraison contrôlé se basant sur l’incorporation d’un nanovecteur dans une matrice hydrogel dans le but de combler les lacunes des systèmes se basant sur un vecteur uniquement. Une telle combinaison pourrait permettre un contrôle accru du relargage par stabilisation réciproque. Plus spécifiquement, nous avons développé un hydrogel structuré intégrant des liposomes, microgels et nanogels séparément chargés en principes actifs modèles potentiellement relargués de manière contrôlé. Ce contrôle a été obtenu par la modification de différents paramètres tels que la température ainsi que la composition et la concentration en nanovecteurs. Nous avons comparé la capacité de chargement et la cinétique de relargage de la sulforhodamine B et de la rhodamine 6G en utilisant des liposomes de DOPC et DPPC à différents ratios, des nanogels de chitosan/acide hyaluronique et des microgels de N-isopropylacrylamide (NIPAM) à différents ratios d’acide méthacrylique, incorporés dans un hydrogel modèle d’acrylamide. Les liposomes présentaient des capacités de chargement modérés avec un relargage prolongé sur plus de dix jours alors que les nanogels présentaient des capacités de chargement plus élevées mais une cinétique de relargage plus rapide avec un épuisement de la cargaison en deux jours. Comparativement, les microgels relarguaient complétement leur contenu en un jour. Malgré une cinétique de relargage plus rapide, les microgels ont démontré la possibilité de contrôler finement le chargement en principe actif. Ce contrôle peut être atteint par la modification des propriétés structurelles ou en changeant le milieu d’incubation, comme l’a montré la corrélation avec les isothermes de Langmuir. Chaque système développé a démontré un potentiel contrôle du taux de relargage, ce qui en fait des candidats pour des investigations futures.

Produção e caracterização de quitooligossacarídeos produzidos pelo fungo Metarhizium anisopliae e avaliação da citotoxicidade em células tumorais

Chitosan is a natural polymer, biodegradable, nontoxic, high molecular weight derived from marine animals, insects and microorganisms. Oligomers of glucosamine (GlcN) and N-acetylglucosamine (GlcNAc) have interesting biological activities, including antitumor effects, antimicrobial activity, antioxidant and others. The alternative proposed by this work was to study the viability of producing chitooligosaccharides using a crude enzymes extract produced by the fungus Metarhizium anisopliae. Hydrolysis of chitosan was carried out at different times, from 10 to 60 minutes to produce chitooligosaccharides with detection and quantification performed by High Performace Liquid Chromatography (HPLC). The evaluation of cytotoxicity of chitosan oligomers was carried out in tumor cells (HepG2 and HeLa) and non-tumor (3T3). The cells were treated for 72 hours with the oligomers and cell viability investigated using the method of MTT. The production of chitosan oligomers was higher for 10 minutes of hydrolysis, with pentamers concentration of 0.15 mg/mL, but the hexamers, the molecules showing greater interest in biological properties, were observed only with 30 minutes of hydrolysis with a concentration of 0.004 mg/mL. A study to evaluate the biological activities of COS including cytotoxicity in tumor and normal cells and various tests in vitro antioxidant activity of pure chitosan oligomers and the mixture of oligomers produced by the crude enzyme was performed. Moreover, the compound with the highest cytotoxicity among the oligomers was pure glucosamine, with IC50 values of 0.30; 0.49; 0.44 mg/mL for HepG2 cells, HeLa and 3T3, respectively. Superoxide anion scavenging was the mainly antioxidant activity showed by the COS and oligomers. This activity was also depending on the oligomer composition in the chitosan hydrolysates. The oligomers produced by hydrolysis for 20 minutes was analyzed for the ability to inhibit tumor cells showing inhibition of proliferation only in HeLa cells, did not show any effect in HepG2 cells and fibroblast cells (3T3)

Suivi par élastographie ultrasonore après réparation endovasculaire d’anévrisme aorto-iliaque : étude de faisabilité in vivo

Les maladies cardiovasculaires sont la première cause de mortalité dans le monde et les anévrismes de l’aorte abdominale (AAAs) font partie de ce lot déplorable. Un anévrisme est la dilatation d’une artère pouvant conduire à la mort. Une rupture d’AAA s’avère fatale près de 80% du temps. Un moyen de traiter les AAAs est l’insertion d’une endoprothèse (SG) dans l’aorte, communément appelée la réparation endovasculaire (EVAR), afin de réduire la pression exercée par le flux sanguin sur la paroi. L’efficacité de ce traitement est compromise par la survenue d’endofuites (flux sanguins entre la prothèse et le sac anévrismal) pouvant conduire à la rupture de l’anévrisme. Ces flux sanguins peuvent survenir à n’importe quel moment après le traitement EVAR. Une surveillance par tomodensitométrie (CT-scan) annuelle est donc requise, augmentant ainsi le coût du suivi post-EVAR et exposant le patient à la radiation ionisante et aux complications des contrastes iodés. L’endotension est le concept de dilatation de l’anévrisme sans la présence d’une endofuite apparente au CT-scan. Après le traitement EVAR, le sang dans le sac anévrismal coagule pour former un thrombus frais, qui deviendra progressivement un thrombus plus fibreux et plus organisé, donnant lieu à un rétrécissement de l’anévrisme. Il y a très peu de données dans la littérature pour étudier ce processus temporel et la relation entre le thrombus frais et l’endotension. L’étalon d’or du suivi post-EVAR, le CT-scan, ne peut pas détecter la présence de thrombus frais. Il y a donc un besoin d’investir dans une technique sécuritaire et moins coûteuse pour le suivi d’AAAs après EVAR. Une méthode récente, l’élastographie dynamique, mesure l’élasticité des tissus en temps réel. Le principe de cette technique repose sur la génération d’ondes de cisaillement et l’étude de leur propagation afin de remonter aux propriétés mécaniques du milieu étudié. Cette thèse vise l’application de l’élastographie dynamique pour la détection des endofuites ainsi que de la caractérisation mécanique des tissus du sac anévrismal après le traitement EVAR. Ce projet dévoile le potentiel de l’élastographie afin de réduire les dangers de la radiation, de l’utilisation d’agent de contraste ainsi que des coûts du post-EVAR des AAAs. L’élastographie dynamique utilisant le « Shear Wave Imaging » (SWI) est prometteuse. Cette modalité pourrait complémenter l’échographie-Doppler (DUS) déjà utilisée pour le suivi d’examen post-EVAR. Le SWI a le potentiel de fournir des informations sur l’organisation fibreuse du thrombus ainsi que sur la détection d’endofuites. Tout d’abord, le premier objectif de cette thèse consistait à tester le SWI sur des AAAs dans des modèles canins pour la détection d’endofuites et la caractérisation du thrombus. Des SGs furent implantées dans un groupe de 18 chiens avec un anévrisme créé au moyen de la veine jugulaire. 4 anévrismes avaient une endofuite de type I, 13 avaient une endofuite de type II et un anévrisme n’avait pas d’endofuite. Des examens échographiques, DUS et SWI ont été réalisés à l’implantation, puis 1 semaine, 1 mois, 3 mois et 6 mois après le traitement EVAR. Une angiographie, un CT-scan et des coupes macroscopiques ont été produits au sacrifice. Les régions d’endofuites, de thrombus frais et de thrombus organisé furent identifiées et segmentées. Les valeurs de rigidité données par le SWI des différentes régions furent comparées. Celles-ci furent différentes de façon significative (P < 0.001). Également, le SWI a pu détecter la présence d’endofuites où le CT-scan (1) et le DUS (3) ont échoué. Dans la continuité de ces travaux, le deuxième objectif de ce projet fut de caractériser l’évolution du thrombus dans le temps, de même que l’évolution des endofuites après embolisation dans des modèles canins. Dix-huit anévrismes furent créés dans les artères iliaques de neuf modèles canins, suivis d’une endofuite de type I après EVAR. Deux gels embolisants (Chitosan (Chi) ou Chitosan-Sodium-Tetradecyl-Sulfate (Chi-STS)) furent injectés dans le sac anévrismal pour promouvoir la guérison. Des examens échographiques, DUS et SWI ont été effectués à l’implantation et après 1 semaine, 1 mois, 3 mois et 6 mois. Une angiographie, un CT-scan et un examen histologique ont été réalisés au sacrifice afin d’évaluer la présence, le type et la grosseur de l’endofuite. Les valeurs du module d’élasticité des régions d’intérêts ont été identifiées et segmentées sur les données pathologiques. Les régions d’endofuites et de thrombus frais furent différentes de façon significative comparativement aux autres régions (P < 0.001). Les valeurs d’élasticité du thrombus frais à 1 semaine et à 3 mois indiquent que le SWI peut évaluer la maturation du thrombus, de même que caractériser l’évolution et la dégradation des gels embolisants dans le temps. Le SWI a pu détecter des endofuites où le DUS a échoué (2) et, contrairement au CT-scan, détecter la présence de thrombus frais. Finalement, la dernière étape du projet doctoral consistait à appliquer le SWI dans une phase clinique, avec des patients humains ayant déjà un AAA, pour la détection d’endofuite et la caractérisation de l’élasticité des tissus. 25 patients furent sélectionnés pour participer à l’étude. Une comparaison d’imagerie a été produite entre le SWI, le CT-scan et le DUS. Les valeurs de rigidité données par le SWI des différentes régions (endofuite, thrombus) furent identifiées et segmentées. Celles-ci étaient distinctes de façon significative (P < 0.001). Le SWI a détecté 5 endofuites sur 6 (sensibilité de 83.3%) et a eu 6 faux positifs (spécificité de 76%). Le SWI a pu détecter la présence d’endofuites où le CT-scan (2) ainsi que le DUS (2) ont échoué. Il n’y avait pas de différence statistique notable entre la rigidité du thrombus pour un AAA avec endofuite et un AAA sans endofuite. Aucune corrélation n’a pu être établie de façon significative entre les diamètres des AAAs ainsi que leurs variations et l’élasticité du thrombus. Le SWI a le potentiel de détecter les endofuites et caractériser le thrombus selon leurs propriétés mécaniques. Cette technique pourrait être combinée au suivi des AAAs post-EVAR, complémentant ainsi l’imagerie DUS et réduisant le coût et l’exposition à la radiation ionisante et aux agents de contrastes néphrotoxiques.

Nanopartículas de alginato como sistema de liberação para o herbicida clomazone

In this paper, we describe the preparation of alginate nanoparticles as a delivery system for the herbicide clomazone. Two different methods were investigated and characterized by size distribution, zeta potencial, pH and in vitro release. The alginate/AOT nanoparticles had higher rates of association of the herbicide clomazone than alginate/chitosan nanoparticles. Clomazone release profile, showed a significant difference in release behavior of pure herbicide in solution when compared with herbicide loaded in both alginate nanoparticles. This study is important to construct a biodegradable release system using herbicide for later release into more specific targets, avoiding contamination of environmental matrices.

Development of multifunctional lipid nanocapsules for the co-delivery of paclitaxel and CpG-ODN in the treatment of glioblastoma

International audience

Estudo da permeação em membranas quitosana

This study proposes to do a study on the mathematical modeling of permeation of films based on chitosan. To conduct the study were obtained membranes with various compositions: a virtually pure membrane-based chitosan; one of chitosan associated with poly (ethylene oxide (PEO). The membranes of pure chitosan were treated with plasma in atmospheres of oxygen, argon and methane. The various types of films were characterized as to its permeation regarding sufamerazina sodium. In the process of mathematical modeling were compared the standard method of obtaining the coefficient of permeation recital straight down the slope of the plot obtained by extinction / time with a the integration process of numerical permeability rate will be calculated from the spectroscopy UV

Modificação de membranas de quitosana por plasma para uso biológico

Chitosan membranes have been modified by plasma, utilizing the following gases: nitrogen (N2), methane (CH4), argon (Ar), oxygen (O2) and hydrogen. The modified membranes by plasma were compared to the unmodified ones. The membranes were characterized by absorption assay, contact angle, atomic force microscopy (AFM). Also, permeability assay of sodium sulfamerazine from such membranes were carried out. Through the absorption assay and contact angle it was possible to obtain information of the wettability of the membranes and what changes the plasma treatment can promote in relation to it. The plasma treatment using oxygen promoted increase of the wetability and swelling while the samples treated with methane decrease of the wetability and swelling. Through the Optical Emission Spectroscopy (OES) it was possible to identify which species were present in the plasma during the treatment. And through the AFM analysis it was possible to observe the changes nanotopography occurred on the surface of the samples. Permeability assay were archived for all treated membranes and compared to no treated ones. Due to that assay it was possible verify which the plasma treatment increased the permeability spectrum of the membranes which has varied from 1,4548 *10-5cm2.min-1 to 2,7713*10-5cm2.min-1. Chitosan membranes with permeability varied are importance in systems drug delivery, to liberate a wide variety of drugs

Polymeric alginate nanoparticles containing the local anesthetic bupivacaine

Bupivacaine (BVC; S75-R25, NovaBupichitosan nanoparticle formulations containing BVC (0.5%). The amounts of BVC associated in the alginate/AOT and alginate/chitosan nanoparticles were 87 +/- 1.5 and 76 +/- 0.9%, respectively. The average diameters and zeta potentials of the nanoparticles were measured for 30 days, and the results demonstrated the good stability of these particles in solution. The in vitro release kinetics showed a different behavior for the release profile of BVC in solution, compared with BVC-loaded alginate nanoparticles. In vitro and in vivo assays showed that alginate-chitosan BVC (BVC(ALG-CHIT)) and alginate-AOT BVC (BVC(ALG-AOT)) presented low cytotoxicity in 3T3-fibroblasts, enhanced the intensity, and prolonged the duration of motor and sensory blockades in a sciatic nerve blockade model.

Síntese verde de nanopartículas de prata a partir de extrato aquoso do tubérculo de Curcuma longa associadas à quitosana e avaliação da atividade antitumoral in vitro em câncer de pele não melanoma (linhagem A431)

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação Nanociência e Nanobiotecnologia, 2016.

Dual Quorum Quenching Capsules: Disrupting two bacterial communication pathways that lead to virulence

Healthcare Associated Infections (HAIs) in the United States, are estimated to cost nearly $10 billion annually. And, while device-related infections have decreased, the 60% attributed to pneumonia, gastrointestinal pathogens and surgical site infections (SSIs) remain prevalent. Furthermore, these are often complicated by antibacterial resistance that ultimately cause 2 million illnesses and 23,000 deaths in the US annually. Antibacterial resistance is an issue increasing in severity as existing antibiotics are losing effectiveness, and fewer new antibiotics are being developed. As a result, new methods of combating bacterial virulence are required. Modulating communications of bacteria can alter phenotype, such as biofilm formation and toxin production. Disrupting these communications provides a means of controlling virulence without directly interacting with the bacteria of interest, a strategy contrary to traditional antibiotics. Inter- and intra-species bacterial communication is commonly called quorum sensing because the communication molecules have been linked to phenotypic changes based on bacterial population dynamics. By disrupting the communication, a method called ‘quorum quenching’, bacterial phenotype can be altered. Virulence of bacteria is both population and species dependent; each species will secrete different toxic molecules, and total population will affect bacterial phenotype9. Here, the kinase LsrK and lactonase SsoPox were combined to simultaneously disrupt two different communication pathways with direct ties to virulence leading to SSIs, gastrointestinal infection and pneumonia. To deliver these enzymes for site-specific virulence prevention, two naturally occurring polymers were used, chitosan and alginate. Chitosan, from crustacean shells, and alginate, from seaweed, are frequently studied due to their biocompatibility, availability, self-assembly and biodegrading properties and have already been verified in vivo for wound-dressing. In this work, a novel functionalized capsule of quorum quenching enzymes and biocompatible polymers was constructed and demonstrated to have dual-quenching capability. This combination of immobilized enzymes has the potential for preventing biofilm formation and reducing bacterial toxicity in a wide variety of medical and non-medical applications.